import java.util.LinkedList;
import java.util.Queue;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * Date: 2025-02-03
 * Time: 20:50
 */
public class MyStack {
    private Queue<Integer> qu1;
    private Queue<Integer> qu2;
    public MyStack() {
        qu1  = new LinkedList<>();
        qu2  = new LinkedList<>();
    }

    public void push(int x) {
        if (empty()){
            qu1.offer(x);
            return;
        }
        if (!qu1.isEmpty()){
            qu1.offer(x);
        }else {
            qu2.offer(x);
        }
    }

    public int pop() {
        if (empty()){
            return -1;
        }
        if (!qu1.isEmpty()){
            int size = qu1.size();
            while (size-1 != 0){
                qu2.offer(qu1.poll());
                size--;
            }
            return qu1.poll();
        }else {
            int size = qu2.size();
            while (size - 1 != 0){
                qu1.offer(qu2.poll());
                size--;
            }
            return qu2.poll();
        }
    }

    public int top() {
        if (empty()){
            return -1;
        }
        if (!qu1.isEmpty()){
            int size = qu1.size();
            int tmp = -1;
            while (size != 0){
                tmp  = qu1.poll();
                qu2.offer(tmp);
                size--;
            }
            return tmp;
        }else {
            int size = qu2.size();
            int tmp = -1;
            while (size != 0){
                tmp = qu2.poll();
                qu1.offer(tmp);
                size--;
            }
            return tmp;
        }
    }

    public boolean empty() {
        return qu1.isEmpty() && qu2.isEmpty();
    }
}
